This invention relates to tufting machines and more particularly to cut pile staggered needle tufting machines for producing very low pile height cut pile fabrics.
In copending U.S. patent application Ser. No. 212,316 filed Dec. 3, 1980, now U.S. Pat. No. 4,303,025 a cut pile tufting machine is disclosed in which the needle plate fingers are oscillated in timed relationship with the hooks and needles to support the backing material during needle penetration and to withdraw from the plane of needle reciprocation as the hooks move across the needles to seize loops of yarn therefrom. By providing for the withdrawal of the needle plate fingers from the path of movement of the needles after the fingers have fulfilled their function of supporting the backing material during penetration, a path of movement for the hooks which lies at or closely adjacent to the opposing face of the backing material is made available so that the underside of the bill of the hook, which is the cutting edge for the cut pile blade, is closely adjacent to the underside of the backing material. Thus, very low pile fabric can be produced.
In apparatus disclosed in the aforesaid application all of the needles lie in a common vertical plane and thus so too do the points of the hooks which cooperate therewith. For this reason all of the needle plate fingers are aligned. However, for a narrow gauge machine, because of space limitations it becomes necessary for the needles to be divided into spaced rows with the needles in each row staggered relatively to the needles in the other row. In this case the hooks must have bills which are likewise staggered so that the hooks cooperate with the respective needles in the different rows. Moreover, in order for the needle plate fingers to perform their intended function of supporting the backing material during penetration by the needles, the fingers must have a configuration for providing support adjacent the penetration points of all the needles.
Prior art close gauge staggered needle machines, to provide the required backing fabric support, provided needle plate fingers of various configurations. For example, in U.S. Pat. No. 3,492,956, the fingers have double off set portions intermediate their length with adjacent fingers alternately oriented in opposite dispositions so that the off sets are disposed about the needles in the row remote from the needle plate. In U.S. Pat. No. 3,064,600, the fingers have double off set portions adjacent the needle plate and are alternately oriented so that the off sets are disposed about the needles in the row adjacent the needle plate. In U.S. Pat. No. 2,976,829, the fingers have single off set portions which are oriented so that the off sets are disposed about the needles in the row adjacent the needle plate. In another arrangement fingers having single off set portions are disposed so that alternate pairs of fingers extend to form a "Y" configuration and the needles in the row remote from the needle plate are disposed within the fork of the "Y".
In each of these constructions the spacing between adjacent fingers of alternate pairs at the needle row remote from the needle plate (hereafter back row) is narrower than the thickness of the needles in the row adjacent the needle plate (hereafter front row), this being especially due to the inclination of the needles in the needle bar. Thus, the prior art needle plate finger constructions cannot be withdrawn from the path of movement of the needles for providing the required path for the hooks to be closely adjacent the backing material. Consequently, the prior art finger constructions are not capable of providing very low pile height when the needle gauge is narrow, i.e. in the order of 1/10 inch and narrower.